Sealed rolling bearings are not new per se. The use of seals to preclude entry of external contaminants, such as water and dust and against the leakage of lubricant grease are common and typically comprise sealing systems at one or both axial ends of the annular space between the bearing rings. In accordance with some prior known sealing systems, the seal comprises one or more flexible lips carried by a rigid reinforcing shield secured in an angularly immobile fashion to one of the bearing rings and producing a sliding seal between the bearing rings in both the axial and radial directions. The seal may be of the type either directly engaging the other ring usually utilizing only one reinforcing shield or indirectly by means of a second reinforcing shield secured as a unit to the other ring and provided with sliding faces.
In both instances, that is, in the case of single or double shielded sealing assemblies, precise axial positioning of the sealing system is essential to achieve the desired sealing action. Otherwise the axial seal will become ineffective and all or part of the sealing action will be destroyed.
It has been found that in prior known bearing assemblies, precise and correct axial positioning of the sealing system is a very complex and costly procedure and requires very careful and precise working of the housing seats to very close and tight tolerances in order to produce the interferences which ensures that the sealing systems are both radially and axially immobilized by friction.